The ability to obtain high-resolution, live-cell images and movies is essential for understanding biological processes and how they are perturbed by disease or mutation. This proposal is for the purchase of an Olympus Disc Scan Unit (DSU) confocal microscope system. Unlike laser-scanning confocal microscopy, the Olympus DSU system uses a white light source, thus dramatically reducing the initial cost and maintenance of the system. To compensate for the lower light intensity available from white-light sources, the Olympus DSU system uses a highly sensitive cooled charged-couple device (CCD) camera to capture fluorescence signals. Out-of-focus light is eliminated by the spinning disc with precisely defined slits that create virtual pin-hole illumination. Fast image acquistion (up to 15 frames/sec) and lowered phototoxicity from spinning disc illumination combine to allow high-quality imaging of both fixed and live cells. The Olympus DSU system will be housed in the Department of Genetics and used by investigators for a variety of projects funded by NIH R01 grants. These include imaging of hundreds of GFP-fusion proteins in Drosophila tissues (Cooley), antibody localization in mouse and C. elegans germline cells (Reinke, Sweasy), cell migration in C. elegans (Stern), localization of mutant forms of PDGF receptor in cells treated with ligands (DiMaio), phosphoinositide signaling in cultured cells (H. Sun), and live imaging of developing zebrafish kidneys (Z. Sun). The Olympus DSU system will replace two out-dated, non-motorized fluorescence microscopes that can no longer produce data essential for these projects. It will also provide a much-needed alternative to expensive laser-scanning confocal imaging, especially in cases where the intensity of fluorescence signals is not limiting. Furthermore, the system will allow ready access to time-lapse microscopy, again with a reduced cost compared to laser-based systems. [unreadable] [unreadable] [unreadable]